Carburetor metering device



H.- A. WOODS n 7 2,375,160

CARBURETOR METERING, DEVICE May 1, 1945.

Filed Oct. 16, 1942 I'NVENTOR HERBERT A.WOO DS $MAQJ U N ATTORNEYPatented May 1, 1945 2,375,160 cannuna'ron METERING DEVIQE Herbert A.Woods, St. Louis, Mo.,

Carter Carburetor Corporation, St.

asslgnor to Louis, Mo,

a corporation of Delaware Application October 16, 1942, Serial No.462,235 3 Claims. 261-44) This invention relates to carburetors forinternal combustion engines and consists particuthe fuel bowl. IAS thecarburetor is heated, thisrestriction may be obstructed by fuel bubblesand, furthermore, the more or less segregated body of fuel in the mainnozzle passage is susceptible to boiling, particularly after the enginehas stopped. which causes liquid fuel to be spilled into the carburetorand intake manifold. This condition, known in the industry aspercolation" results in hard starting until such excess fuel evaporatesor is carried from the manifold.

It is an object of the present invention, accordingly, to provide acarburetor in which the main fuel passages have substantiallyunrestricted communication with the fuel bowl and the metering of fuelis efiected at the discharge end of the nozzle. Another object is toprovide for metering fuel at the discharge end of the main fuel nozzlewithout, at the same time, appreciably varying the main supp y of airthrough the carburetor.

These objects and other more detailed objects hereafter appearing areattained substantially by the device illustrated in the accompanyingdrawn in which Fig. 1 is a sectional view of a carburetor embodying thenovel fuel metering arrangement.

Fig. 2 is an outside elevation of the carburetor showing the means forbaflle.

Figs. 3 and 4 are enlarged, detail views showing the nozzle and fuelmetering baflle in different positions.

Fig. 5 is a detail section taken on line 5-5 of Fig.4.

The carburetor illustrated has a downdraft inoperating the meteringtrolling the normal level of fuel in, the bowl. A main fuel nozzle itextends from the bowl to a point directly above the center of smallventuri 6 and has a tip portion with a fuel outlet opening H facinggenerally across the direction of air flow, and an air inlet opening l2facing against the air flow. The nozzle I0 is substantially unrestrictedbelow the fuel level :r-w.

Extending across the mixture conduit above the Venturi tubes is a shaftIE of generally ci:cular cross section but having a central portionimmediately adjacent the tip of nozzle it which is cut out, as at 16, soas to prevent an eccentric face I! to the nozzle tip. On one end ofshaft l5 outside the body of the carburetor there is secured a small armI8 urged counterclockwise by a spring 23 and pinned to a cam followerlink is which slides longitudinally in a guide 20. A follower roller 2!on the end of this link rides on a cam 22 pivoted on the carburetorbody.

The mechanism is arranged so that, as the throttle valve is moved, shafti5 is rotated to vary the relationship of baiiie surface I! and thenozzle tip and thereby vary the effective suction on the nozzle tip and,consequently, the rate of fuel discharge therefrom. The contour of cam22 may be varied to provide for proper proportioning of the mixture atall throttle positions. Generally, this cam will be irregular in shape.

When the throttle is fully opened, the position of shaft l5 will be asin Fig. 3, with baiiie face l1 substantially overlying and. shieldingthe tip of the nozzle so that increased suction is applied to the nozzleoutlet. This position, furthermore,

restricts the entry of air into inlet hole I2. The position of maximumleanness is shown in Fig. 1 in which the baflie face extend beneath thenozzle tip so as to increase the pressure on the nozzle outlet. Theposition of the bailie in Fig. 4 is intermediate. Cam 22 is shaped toprovide for the proper mixture enrichment as specified by the enginemanufacturer and to obtain the maximum economy or power as determined bydynamometer tests. For instance, as the throttle is opened from theposition in Fig. 1, shaft [5 may remain stationary during the partthrottle positions to provide best economy, and as the throttleapproaches full open position, shaft l5 may rotate clockwise to providea richer or power mixture.

The major portion of shaft l5 being of circular section, rotation ofthis shaft does not materially affect the .total quantity of air flowingthrough the carburetor. The small cut-out portion I6 into which thenozzle tip extends replaces the small primary venturi into which thenozzle extends in some carburetors. The carburetor may be provided withsuitable auxiliary fuel systems such as the idling, accelerator, andstep-up economizer devices generally used.

The free communication between fuel bowl and the main nozzle insuresthat the temperature of fuel in the nozzle will be substantially thesame as that of the larger body of fuel in the bowl and, consequently,the temperature of the home fuel does not rise so rapidly after theengine has stopped and percolation is substantially reduced oreliminated. In any particular carburetor, baiiie face l1 need not beadjustable to the extreme positions shown in the figures, these beingmerely illustrative of the possibilities of the device. Of course, thesize of holes II and II in the nozzle tip may be varied to provide forthe proper mixture proportions. The fuel metering arrangement is,accordingly, quite flexible and permits accurate calibration of thecarburetor.

The arrangement may be modified in various respects as will occur tothose skilled in the art and the exclusive use of all modifications ascome within the scope of the appended claims is contemplated.

I claim:

1. In a carburetor air induction conduit, a constant level chamber, afuel nozzle projecting into said conduit and having a tip portion abovethe fuel level, said portion having a discharge opening facing acrossthe direction of air fiow and an air inlet opening facing against theair how, and a relatively small, generally cylindrical shaft extendingacross said conduit and having a deformed part immediately adjacent saidtip por- 35 tion and presenting an eccentric face thereto, said baiilebeing rotatable to variably affect the air fiow past said nozzleopenings and, consequently, the metering of fuel through said nozzle. 2.In a carburetor, an induction conduit, 9. throttle, a fuel nozzle havingan orifice opening into said conduit, a generally cylindrical shaftextending transversely into said conduit with its axis close to saidorifice and having a cut-out part providing a face substantially on achord of the shaft immediatclyconfronting said orifice, and means torotate said shaft to alter the position of said face relative to saidopening and thereby affect the functioning thereof, the diameter of saidshaft being substantially less than that of said conduit and said faceextending only the width of said nozzle so that only the air fiowsubstantially in line with said opening is affected by movements of saidshaft. 3. In a carburetor, an induction conduit, :1. throttle, a.venturi, a fuel nozzle having an orifice arranged to discharge fuel intosaid conduit, a shaft extending across said conduit, said shaft having aportion cut-out to form an eccentric face immediately adjacent said fueloutlet opening, and means operable by movement of said throttle torotate said shaft to variably divert the air flow away from said nozzleand thereby affect the nozzle fuel discharge, the eccentric face of saidshaft extending only substantially the width of said nozzle so thatrotation of said shaft does not substantially affect the total air flowthrough said conduit.

HERBERT A. WOODS.

